samedi 29 octobre 2016

Image above: The Soyuz MS-01 spacecraft departs the International Space Station on time carrying three Expedition 49 crew members back to Earth. Image Credit: NASA TV.

NASA astronaut Kate Rubins of NASA, Anatoly Ivanishin of the Russian Federal Space Agency (Roscosmos) and Takuya Onishi of the Japan Aerospace Exploration Agency undocked from the International Space Station at 8:35 p.m. EDT to begin their journey home.

Ivanishin, the Soyuz commander, is at the controls of the MS-01 spacecraft. The trio’s spacecraft completed the first flight to station for the upgraded Soyuz MS-01 when it launched in July.

The crew is scheduled to land at 11:59 p.m. southeast of Dzhezkazgan, Kazakhstan.

Image above: The Soyuz MS-01 spacecraft rests at its Rassvet module docking port. The Expedition 49 crew members are inside the spacecraft preparing for their undocking and landing in Kazakhstan tonight. Image Credit: NASA TV.

As the Soyuz MS-01 undocked, Expedition 50 officially began on the station under the command of NASA astronaut Shane Kimbrough. He and Flight Engineers Sergey Ryzhikov and Andrey Borisenko of Roscosmos, will operate the station for three weeks until the arrival of three new crew members next month
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Expedition 49 Departs from the ISS

NASA TV will air live coverage of the Soyuz MS-01 deorbit burn and landing beginning at 10:45 p.m. Watch live online on NASA’s website: http://www.nasa.gov/ntv

vendredi 28 octobre 2016

(Highlights: Week of Oct. 17, 2016) - Two launches made this a high-traffic week on the International Space Station. It began on Oct. 17 with the launch to the station of two tons of new science investigations and supplies on a Cygnus capsule. The week ended with the arrival of three new crew members. In the meantime, studies on orbit continued on methods to ensure clean water for astronauts in space and in remote locations on Earth.

Image above: NASA astronaut Kate Rubins works on WetLab-2, which enables a variety of life science investigations in space, such as analyzing genes that may indicate infectious disease, cell stress, cellular growth and development and genetic abnormalities. Researchers can also use the system for real-time analysis of air, surface and water samples to monitor for environmental changes on the station. Image Credit: NASA.

NASA astronaut Kate Rubins deployed the Microbial Monitoring System hardware as part of the Water Monitoring Suite experiment, collecting five water samples for testing. This new technology can quickly detect and identify potentially harmful microorganisms in the station's water supply. If successful, it will ensure that crew members can perform real time tests and monitor the safety of their water on future missions.

Using current technology, it can take a week to search for harmful bacteria. With the new Microbial Monitoring System, it could take less than an hour. This would be invaluable to travelers in space where water is a very limited and precious commodity, and would also help millions of people on Earth without access to clean water. Equipment that is fast and simple to use can improve water quality monitoring in remote areas.

Image above: A Cygnus capsule carrying more than two tons of supplies and scientific investigations approaches the International Space Station as crew members remotely reach out with Canadarm-2 to capture the spacecraft for docking. Image Credit: NASA.

JAXA (Japan Aerospace Exploration Agency) astronaut Takuya Onishi started the 11th round of JAXA's High Quality Protein Crystal Growth (JAXA PCG) experiment. He installed two canisters containing 48 protein samples into the Protein Crystallization Research Facility, which will grow protein crystals for the next few weeks to search for methods to improve the quality of crystals grown in microgravity.

Protein crystals have been grown and studied in space for many years and the benefits are widespread. Proteins crystallized in microgravity are better organized and larger than those produced on Earth, where gravity can interfere with their formation. Detailed analysis of high-quality protein crystal structures is useful in designing new pharmaceuticals to combat disease and contributes to a range of commercial aspects including industrial and energy sectors.

Image above: Russian cosmonauts Andrey Borisenko and Sergey Ryzhilkov open the hatch to enter the space station soon after arriving in a Soyuz spacecraft. The station will be their home -- along with NASA astronaut Shane Kimbrough -- for the next four months. Image Credit: NASA.

Onishi also completed his final session of the investigation into the effect of long-term microgravity exposure on cardiac autonomic function by analyzing 48 hours of electrocardiogram (Biological Rhythms 48hrs). Using a special electrocardiograph monitor worn by Onishi, this study collects data analyzing an astronaut's heart patterns and other physical activity over a period of 48 hours. His readings, combined with data measured from previous space station crew members, will be analyzed to improve the health care technology for space travelers on long-duration missions. The data and technology created for astronauts as a results of this investigation could also be used on Earth to promote a healthy lifestyle.

Progress was made on other investigations and facilities this week, including ISS Ham, Tropical Cyclone, Group Combustion, ACE T-1, Meteor, WetLab-2, Personal CO2 Monitors, MDCA, MERLIN-2, Veggie and Manufacturing Device.

Globular clusters offer some of the most spectacular sights in the night sky. These ornate spheres contain hundreds of thousands of stars, and reside in the outskirts of galaxies. The Milky Way contains over 150 such clusters — and the one shown in this NASA/ESA Hubble Space Telescope image, named NGC 362, is one of the more unusual ones.

As stars make their way through life they fuse elements together in their cores, creating heavier and heavier elements — known in astronomy as metals — in the process. When these stars die, they flood their surroundings with the material they have formed during their lifetimes, enriching the interstellar medium with metals. Stars that form later therefore contain higher proportions of metals than their older relatives.

By studying the different elements present within individual stars in NGC 362, astronomers discovered that the cluster boasts a surprisingly high metal content, indicating that it is younger than expected. Although most globular clusters are much older than the majority of stars in their host galaxy, NGC 362 bucks the trend, with an age lying between 10 and 11 billion years old. For reference, the age of the Milky Way is estimated to be above 13 billion years.

Hubble Space Telescope. Image Credit: NASA

This image, in which you can view NGC 362’s individual stars, was taken by Hubble’s Advanced Camera for Surveys (ACS).

Image above: Data from CLOUD has been used to build a model of aerosol production, which could help researchers establish the main cause of new particle formation in the troposphere, and narrow predictions for global temperature rise. (Image: Maximillien Brice/ CERN).

According to the Intergovernmental Panel on Climate Change, the Earth’s mean temperature is predicted to rise by between 1.5 – 4.5 °C for a doubling of carbon dioxide in the atmosphere, which is expected by around 2050. One of the main reasons for this large uncertainty, which makes it difficult for society to know how best to act against climate change, is a poor understanding of aerosol particles in the atmosphere and their effects on clouds.

To date, all global climate models use relatively simple parameterisations for aerosol production that are not based on experimental data. Now, data collected by CLOUD have been used to build a model of aerosol production based solely on laboratory measurements. This more robust understanding of the nucleation process that gives rise to aerosols has allowed researchers to establish the main causes of new particle formation throughout the troposphere, and could narrow the variation in projected global temperature rise.

“This marks a big step forward in the reliability and realism of how models describe aerosols and clouds,” says CLOUD spokesperson Jasper Kirkby. “It’s addressing the largest source of uncertainty in current climate models and building it on a firm experimental foundation of the fundamental processes.”

Aerosol particles form when certain trace vapours in the atmosphere cluster together, and grow to a sufficient size that they can seed cloud droplets. Higher concentrations of aerosol particles make clouds more reflective and long-lived, thereby cooling the climate, and it is thought that the increased concentration of aerosols caused by air pollution since the start of industrial period has offset a large part of the warming caused by greenhouse-gas emissions. Until now, however, an incomplete understanding of how aerosols form has hampered efforts to estimate the total forcing of climate from human activities.

In the latest work, published in Science, researchers built a global model of aerosol formation using CLOUD-measured nucleation rates involving sulphuric acid, ammonia, ions and organic compounds. Although sulphuric acid has long been known to be important for nucleation, the results show for the first time that observed concentrations of particles throughout the atmosphere can be explained only if additional molecules - organic compounds or ammonia - participate in nucleation. The results also show that ionisation of the atmosphere by cosmic rays accounts for nearly one-third of all particles formed, although small changes in cosmic rays over the solar cycle do not affect aerosols enough to influence today’s polluted climate significantly.

CLOUD Experiment - How it works -

Video above: A brief tour of the CLOUD experiment at CERN, and its scientific aims. (Video: Noemi Caraban/CERN).

“This is a huge step for atmospheric science,” says lead author Ken Carslaw of the University of Leeds, UK. “It’s vital that we build climate models on experimental measurements and sound understanding, otherwise we cannot rely on them to predict the future. Eventually, when these processes get implemented in climate models, we will have much more confidence in aerosol effects on climate.”

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

While scanning the sky to measure the position of over one billion stars in our Galaxy, ESA's Gaia satellite has detected two rare instances of stars whose light was temporarily boosted by other celestial objects passing across their lines of sight. One of these stars is expected to brighten again soon. Gaia's measurements will be instrumental to learn more about the nature of these 'cosmic magnifying glasses'.

The two events were identified in July and August 2016, respectively, by the Gaia Photometric Science Alerts Team, who scrutinise the Gaia data looking for astronomical sources that are, for a short period of time, much brighter than usual.

So far, the team has detected over a thousand transient sources, most of which are stars undergoing a major outburst, or supernova explosions at the end of a star's life. The discoveries are now routinely announced to the astronomical community, via the Gaia Photometric Science Alerts website, so that other astronomers can follow up, in a timely manner, with other telescopes.

On rare occasions, there is also another phenomenon that can produce a sudden boost in a star's brightness: the gravity of other celestial objects that happen to pass between the star and the observer.

According to Albert Einstein's general theory of relativity, gravity causes massive objects – like stars, planets, galaxies or black holes – to bend the fabric of spacetime. This also distorts the paths of light rays passing nearby.

When such a massive object is exactly aligned between a distant source of light and an observer, it acts as a gravitational lens, and the observer may see a dramatic increase (and subsequent decrease) of the source's brightness – much like when we observe something through a magnifying glass. This phenomenon is called gravitational microlensing [1].

"Microlensing of stars in our Galaxy is very useful to dig up objects that don't emit light, like black holes, but can still distort the light coming from background stars," explains Łukasz Wyrzykowski, from the Warsaw University Astronomical Observatory, Poland, and a member of the Gaia Photometric Science Alerts Team.

"Stars, multiple stellar systems and even planetary systems can act as gravitational lenses, each giving rise to a different pattern of variations to the brightness of the background star."

Gaia's first detection of such an event, classified as Gaia16aua and nicknamed by the team Auala, after a small village in Samoa, is a faint star of magnitude 19 that suddenly brightened by two magnitudes [2]. The brightness rise and subsequent decrease were observed independently, both by Gaia and by the ground-based Optical Gravitational Lensing Experiment (OGLE). The ground-based observations provided a longer and denser baseline of data, confirming that the brightness variations observed by Gaia were actually caused by a microlensing event.

The effect of gravitational lensing depends on the mass of the lens – as well as on the relative distances between source, lens and observer. In the case of a nearly perfect alignment between source, lens and observer, the brightness of the background star increases and its position in the sky appears slightly shifted. By measuring both these tiny effects, it is possible to estimate the mass of the unseen object that is acting as a lens.

What makes it special to find microlensing events with Gaia, a mission whose scientific goal is to measure stellar positions in the sky to unprecedented accuracy, is that astronomers will be able to measure the motion of the source on the sky as its brightness varies due to gravitational lensing.

"By combining Gaia's information on the changes in position of the background star with ground-based data of its brightness variations, we will be able to estimate the mass of the object that bent its light with very good precision," explains Timo Prusti, Gaia Project Scientist at ESA.

"The lens in this case could be either a star or a black hole, and further analysis will tell."

Gaia's second microlensing event, classified as Gaia16aye and nicknamed Ayers Rock after the famous landmark in Australia, is perhaps even more intriguing. After the initial discovery by Gaia of an anomalous increase in the brightness of this magnitude 14.5 star last August, astronomers started observing it with many telescopes on the ground, revealing a rather peculiar pattern of brightness variations.

Instead of a single rise and fall, the star has undergone two consecutive brightness peaks of roughly two magnitudes, then became fainter for a few weeks. It later exhibited a sharp increase to magnitude 12 and rapidly declined again.

"This intricate pattern suggests that the star is not being lensed by a single object but rather by a binary system," says Przemek Mróz, a PhD student at Warsaw Astronomical Observatory.

The star's brightness is expected to undergo a final surge in the coming weeks, reaching around magnitude 12 for a few hours, and frequent observations are currently being carried out by professional and amateur astronomers across the world. Wyrzykowski and his colleagues are looking forward to more observers, including schools with small telescopes, joining the final phase of this monitoring campaign.

The full data set, along with Gaia's estimate of the star's position, will be instrumental to reveal the mass and nature of the foreground lens.

The astronomers think the culprit is most likely a binary system of stars, but it is also possible that a planet, or even a black hole, are part of the system.

Another peculiarity is that both lensed stars found by Gaia are located in the spiral arms of our Milky Way galaxy – something that is extremely rare.

"Microlensing happens for one in a million stars when we observe towards the Galactic Centre, but only about once in a hundred million for spiral arm stars," explains Wyrzykowski.

"We were extremely lucky to find these two events," adds Simon Hodgkin, head of the Gaia Photometric Science Alerts Team at the Institute of Astronomy in Cambridge, UK.

Gaia mapping the stars of the Milky Way

Over the past couple of decades, astronomers have been regularly observing microlensing of stars using telescopes on Earth, leading to many findings including the discovery of several exoplanets.

While ground-based surveys can only monitor individual patches of the sky, Gaia can now detect these events over the entire celestial sphere, and the combination of different data gathered from ground and space might reveal more information about the nature of these cosmic lenses.

After over two years of Gaia scientific operations, the Photometric Science Alerts Team have developed very efficient algorithms to detect transient events, and are planning to refine these further to improve the efficiency for microlensing detections.

Notes:

[1] In the case of gravitational microlensing, the distortion caused by a foreground object, or lens, to the light coming from a distant source can be observed in terms of a temporary magnification (or de-magnification) of the source's brightness. In the more extreme cases of weak and strong gravitational lensing, deformed or even multiple images of the same source are observed.

[2] The magnitude system is a logarithmic measure of the brightness of astronomical objects. The brighter an object appears, the lower the value of its magnitude, with the brightest objects reaching negative values. A magnitude 15 star is about 4 million times fainter than Sirius, the brightest star in the night sky, which has a magnitude of -1.5.

Satellite engineers have been puzzling over why GPS navigation systems on low-orbiting satellites like ESA’s Swarm sometimes black out when they fly over the equator between Africa and South America. Thanks to Swarm, it appears ‘thunderstorms’ in the ionosphere are to blame.

Launched in 2013, the Swarm trio is measuring and untangling the different magnetic fields that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere – an undertaking of at least four years.

GPS interruptions

As with many satellites, ESA’s three Swarm satellites carry GPS receivers as part of their positioning system so that operators keep them in the correct orbits. In addition, GPS pinpoints where the satellites are making their scientific measurements.

However, sometimes the satellites lose their GPS connection. In fact, during their first two years in orbit, the link was broken 166 times.

A paper published recently describes how Swarm has revealed there is a direct link between these blackouts and ionospheric ‘thunderstorms’, around 300–600 km above Earth.

Claudia Stolle from the GFZ research centre in Potsdam, Germany said, “Ionospheric thunderstorms are well known, but now we have been able to show a direct link between these storms and the loss of connection to GPS.

“This is thanks to Swarm because it is the first time that high-resolution GPS and ionospheric patterns can be detected from the same satellite.”

GPS losses

These thunderstorms occur when the number of electrons in the ionosphere undergoes large and rapid changes. This tends to happen close to Earth’s magnetic equator and typically just for a couple of hours between sunset and midnight.

As its name suggests, the ionosphere is where atoms are broken up by sunlight, which leads to free electrons. A thunderstorm scatters these free electrons, creating small bubbles with little or no ionised material. These bubbles disturb the GPS signals so that the Swarm GPS receivers can lose track.

It transpires that 161 of the lost signal events coincided with ionospheric thunderstorms. The other five were over the polar regions and corresponded to increased strong solar winds that cause Earth’s protective magnetosphere to ‘wobble’.

Resolving the mystery of blackouts is not only good news for Swarm, but also for other low-orbiting satellites experiencing the same problem. It means that engineers can use this new knowledge to improve future GPS systems to limit signal losses.

Christian Siemes, who works at ESA on the mission, said, “In light of this new knowledge, we have been able to tune the Swarm GPS receivers so they are more robust, resulting in fewer blackouts.

Earth's protective shield

“Importantly, we are able to measure variations in the GPS signal which is not only interesting for engineers developing GPS instruments, but also interesting to advance our scientific understanding of upper-atmosphere dynamics.”

ESA’s Swarm mission manager, Rune Floberghagen, added, “What we see here is a striking example of a technical challenge being turned into exciting science, a true essence of an Earth Explorer mission such as Swarm.

“These new findings demonstrate that GPS can be used as a tool for understanding dynamics in the ionosphere related to solar activity. Perhaps one day we will also be able to link these ionospheric thunderstorms with the lightning we see from the ground.”

jeudi 27 octobre 2016

One spacecraft is being packed and readied for the return of three humans to Earth while a cargo craft is being unloaded and settling in for a one-month stay.

The Expedition 49 trio of Commander Anatoly Ivanishin and Flight Engineers Kate Rubins and Takuya Onishi are packing gear and preparing for their return to Earth Saturday night. The veteran cosmonaut and two first-time astronauts will wrap up their mission after 115 days in space.

They will parachute to a landing in Kazakhstan inside the Soyuz MS-01 spacecraft. The ride back to Earth takes about 3-1/2 hours after undocking from the International Space Station.

The Orbital ATK Cygnus is the latest cargo ship to arrive at the International Space Station. It was captured and installed to the Harmony module on Sunday Oct. 23 after a six-day flight that began in Virginia.

The hatches were opened the day it arrived and the crew began unloading over 5,100 pounds of crew supplies and science gear. Cygnus is scheduled to depart in mid-November and release a set of nanosatellites before scientists remotely set fire inside the spacecraft for the Saffire-II experiment.

NASA Television will air coverage of the departure and landing activities, beginning with a change of command ceremony at 3:30 p.m. on Friday, Oct. 28. Expedition 49 Commander Ivanishin will hand over station command to NASA astronaut Shane Kimbrough.

Image above: This photograph shows the first pass of Echo 1, NASA’s first communications satellite, over the Goldstone Tracking Station managed by NASA’s Jet Propulsion Laboratory, in Pasadena, California, in the early morning of Aug. 12, 1960. The movement of the antenna, star trails (shorter streaks), and Echo 1 (the long streak in the middle) are visible in this image. Image Credits: NASA/JPL-Caltech.

Eighty years ago, when interplanetary travel was still a fiction and that fiction looked like Flash Gordon, seven young men drove out to a dry canyon wash in the foothills of the San Gabriel Mountains and helped jump-start the Space Age.

They were out there on Halloween 1936 to try what few people at the time had tried: lighting a liquid rocket engine. It took them four attempts to get a rocket to fire for a glorious three seconds -- though an oxygen hose also broke loose and sent them scampering for safety as it thrashed around.

The result was encouraging enough for this group -- made up of five grad students studying at Caltech and two amateur rocket enthusiasts -- to keep going, to build more rockets that would lead to an institution where they could do this kind of work every day. JPL went on to plant the seeds for America’s rocket program before transitioning into what sat on top of rockets in 1958, when it launched America’s first satellite, Explorer 1. JPL has participated in more than 114 missions to space since its birth, becoming a leader in robotic exploration beyond the moon.

“The dreams and spirit of exploration that originally propelled JPL into the forefront of rocket research and ultimately deep-space exploration continue to this day. I think the pioneers of JPL would be very proud to know that today we have some two dozen spacecraft and instruments studying our solar system, the universe and our home planet, Earth,” said JPL Director Mike Watkins.

Image above: This is what greeted visitors to the Jet Propulsion Laboratory in December 1957, before NASA was created and the lab became one of its centers. There is no sign at this location today -- there is just a stairway that runs up the side of the main administration building (Building 180). The official lab sign has moved farther south, just as the lab itself has expanded farther south out from the base of the San Gabriel Mountains. Image Credits: NASA/JPL.

The path hasn’t always been a straight line, but through all its work, JPL has sought out projects with one foot in the future. Recently rediscovered audio recordings from the JPL archives, for instance, highlight the lab’s involvement in America’s early attempts at satellite communications.

One of these vintage recordings comes from NASA’s first communications satellite, Project Echo, which bounced radio signals off a 10-story-high, aluminum-coated balloon orbiting Earth in 1960. This form of “passive” satellite communication -- which they dubbed a “satelloon” -- was an idea conceived by an engineer from NASA’s Langley Research Center, Hampton, Virginia, and a project managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. JPL’s role involved sending and receiving signals through two of its 85-foot-diameter antennas at the West Coast Goldstone tracking station in the Mojave Desert.

Image above: Echo, NASA’s first communications satellite, was a passive spacecraft based on a balloon design by an engineer at NASA's Langley Research Center in Hampton, Virginia. Made of Mylar, the satellite measured about 100 feet (30 meters) in diameter. It is seen here in an inflation test in Weeksville, North Carolina, in a photograph from Aug. 12, 1960. Image Credits: NASA/GSFC.

The Echo transmissions include a greeting from President Dwight D. Eisenhower, explaining how Echo fit into the U.S. program of peaceful space research accessible to other countries, and a message from then-Senator Lyndon B. Johnson imagining a “not too distant future when one man, one program, can be seen and heard simultaneously in every living room of the world.”

A second recently discovered recording comes from Project Relay, also managed by Goddard, which involved an “active” satellite that received and retransmitted signals on a different frequency. In this audio file from 1963, Jack James, manager of the Mariner program exploring the inner solar system at JPL, speaks with John Glenn, who was then providing astronaut input into the new Apollo program.

JPL -- and NASA -- stopped supporting communications satellite technologies relatively early in the Space Age because commercial enterprises were better poised to take up this work, said JPL historian Erik Conway. But Echo did provide some of the early development work that led to deep-space communications. The antennas at Goldstone later became part of the JPL-managed NASA Deep Space Network -- the “phone company” for nearly every spacecraft that has gone to the moon or beyond.

“What’s amazing about these vintage recordings is that they show how JPL is always evolving,” Conway said. “We’re known now for planetary exploration, but we used to do something completely different. We could be doing something beyond the realm of our current imagination 80 years from now.”

Images comparing vintage photographs of the lab with what those locations look like today, a timeline of JPL’s history and an 80th anniversary calendar celebrating space history can be seen at: http://www.jpl.nasa.gov/history

New results from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission are providing insights into the huge impacts that dominated the early history of Earth’s moon and other solid worlds, like Earth, Mars, and the satellites of the outer solar system.

In two papers, published this week in the journal Science, researchers examine the origins of the moon's giant Orientale impact basin. The research helps clarify how the formation of Orientale, approximately 3.8 billion years ago, affected the moon's geology.

Image above: Orientale basin is about 580 miles (930 kilometers) wide and has three distinct rings, which form a bullseye-like pattern. This view is a mosaic of images from NASA's Lunar Reconnaissance Orbiter. Image Credits: NASA/GSFC/Arizona State University.

Located along the moon's southwestern limb -- the left-hand edge as seen from Earth -- Orientale is the largest and best-preserved example of what's known as a "multi-ring basin." Impact craters larger than about 180 miles (300 kilometers) in diameter are referred to as basins. With increasing size, craters tend to have increasingly complex structures, often with multiple concentric, raised rings. Orientale is about 580 miles (930 kilometers) wide and has three distinct rings, which form a bullseye-like pattern.

Multi-ring basins are observed on many of the rocky and icy worlds in our solar system, but until now scientists had not been able to agree on how their rings form. What they needed was more information about the crater's structure beneath the surface, which is precisely the sort of information contained in gravity science data collected during the GRAIL mission.

The powerful impacts that created basins like Orientale played an important role in the early geologic history of our moon. They were extremely disruptive, world-altering events that caused substantial fracturing, melting and shaking of the young moon's crust. They also blasted out material that fell back to the surface, coating older features that were already there; scientists use this layering of ejected material to help determine the age of lunar features as they work to unravel the moon's complex history.

The Importance of Orientale

Because scientists realized that Orientale could be quite useful in understanding giant impacts, they gave special importance to observing its structure near the end of the GRAIL mission. The orbit of the mission’s two probes was lowered so they passed less than 1.2 miles (2 kilometers) above the crater's mountainous rings.

"No other planetary exploration mission has made gravity science observations this close to the moon. You could have waved to the twin spacecraft as they flew overhead if you stood at the ring's edge," said Sami Asmar, GRAIL project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California.

Of particular interest to researchers has been the size of the initial crater that formed during the Orientale impact. With smaller impacts, the initial crater is left behind, and many characteristics of the event can be inferred from the crater's size. Various past studies have suggested each of Orientale's three rings might be the remnant of the initial crater.

In the first of the two new studies, scientists teased out the size of the transient crater from GRAIL's gravity field data. Their analysis shows that the initial crater was somewhere between the size of the basin's two innermost rings.

"We've been able to show that none of the rings in Orientale basin represent the initial, transient crater," said GRAIL Principal Investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge, lead author of the first paper. "Instead, it appears that, in large impacts like the one that formed Orientale, the surface violently rebounds, obliterating signs of the initial impact."

The analysis also shows that the impact excavated at least 816,000 cubic miles (3.4 million cubic kilometers) of material -- 153 times the combined volume of the Great Lakes.

"Orientale has been an enigma since the first gravity observations of the moon, decades ago," said Greg Neumann, a co-author of the paper at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. "We are now able to resolve the individual crustal components of the bullseye gravity signature and correlate them with computer simulations of the formation of Orientale."

Reproducing the Rings

The second study describes how scientists successfully simulated the formation of Orientale to reproduce the crater's structure as observed by GRAIL. These simulations show, for the first time, how the rings of Orientale formed, which is likely similar for multi-ring basins in general.

"Because our models show how the subsurface structure is formed, matching what GRAIL has observed, we're confident we've gained understanding of the formation of the basin close to 4 billion years ago," said Brandon Johnson of Brown University, Providence, Rhode Island, lead author of the second paper.

The results also shed light on another moon mystery: Giant impacts like Orientale should have dredged up deep material from the moon's mantle, but instead, the composition of the crater's surface is the same as that of the lunar crust. So, scientists have wondered, where did the mantle material go?

The simulation shows that the deep, initial crater quickly collapses, causing material around the outside to flow inward, and covering up the exposed mantle rock.

Artist's view of GRAIL twin satellites. Image Credit: NASA

The new GRAIL insights about Orientale suggest that other ringed basins, invisible in images, could be discovered by their gravity signature. This may include ringed basins hidden beneath lunar maria -- the large, dark areas of solidified lava that include the Sea of Tranquility and the Sea of Serenity.

"The data set we obtained with GRAIL is incredibly rich," said Zuber. "There are many hidden wonders on the moon that we'll be uncovering for years to come."

The twin GRAIL probes were launched in 2011. The mission concluded in 2012.

The GRAIL mission was managed by NASA's Jet Propulsion Laboratory in Pasadena, California, for NASA's Science Mission Directorate in Washington. The mission was part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Alabama. GRAIL was built by Lockheed Martin Space Systems in Denver.

NASA’s New Horizons mission reached a major milestone this week when the last bits of science data from the Pluto flyby – stored on the spacecraft’s digital recorders since July 2015 – arrived safely on Earth.

Having traveled from the New Horizons spacecraft over 3.4 billion miles, or 5.5 billion kilometers (five hours, eight minutes at light speed), the final item – a segment of a Pluto-Charon observation sequence taken by the Ralph/LEISA imager – arrived at mission operations at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, at 5:48 a.m. EDT on Oct. 25. The downlink came via NASA’s Deep Space Network station in Canberra, Australia. It was the last of the 50-plus total gigabits of Pluto system data transmitted to Earth by New Horizons over the past 15 months.

“The Pluto system data that New Horizons collected has amazed us over and over again with the beauty and complexity of Pluto and its system of moons,” said Alan Stern, New Horizons principal investigator from Southwest Research Institute in Boulder, Colorado. “There’s a great deal of work ahead for us to understand the 400-plus scientific observations that have all been sent to Earth. And that’s exactly what we’re going to do—after all, who knows when the next data from a spacecraft visiting Pluto will be sent?”

Because it had only one shot at its target, New Horizons was designed to gather as much data as it could, as quickly as it could – taking about 100 times more data on close approach to Pluto and its moons than it could have sent home before flying onward. The spacecraft was programmed to send select, high-priority datasets home in the days just before and after close approach, and began returning the vast amount of remaining stored data in September 2015.

Bowman said the team will conduct a final data-verification review before erasing the two onboard recorders, and clearing space for new data to be taken during the New Horizons Kuiper Belt Extended Mission (KEM) that will include a series of distant Kuiper Belt object observations and a close encounter with a small Kuiper Belt object, 2014 MU69, on Jan. 1, 2019.

The Data Downlink Challenge

Why did it take more than a year for New Horizons to send back all of the data from the Pluto encounter? Take a minute to learn more about the challenge of sending data from over billions of miles.

Pluto in a Minute: Why Is It Taking So Long to Downlink Data from New Horizons?

Astronomers using observations from NASA's Kepler and Swift missions have discovered a batch of rapidly spinning stars that produce X-rays at more than 100 times the peak levels ever seen from the sun. The stars, which spin so fast they've been squashed into pumpkin-like shapes, are thought to be the result of close binary systems where two sun-like stars merge.

NASA's Kepler, Swift Missions Harvest ‘Pumpkin’ Stars

Video above: Dive into the Kepler field and learn more about the origins of these rapidly spinning stars. Video Credits: Credits: NASA's Goddard Space Flight Center/Scott Wiessinger, producer.

"These 18 stars rotate in just a few days on average, while the sun takes nearly a month," said Steve Howell, a senior research scientist at NASA's Ames Research Center in Moffett Field, California, and leader of the team. "The rapid rotation amplifies the same kind of activity we see on the sun, such as sunspots and solar flares, and essentially sends it into overdrive."

The most extreme member of the group, a K-type orange giant dubbed KSw 71, is more than 10 times larger than the sun, rotates in just 5.5 days, and produces X-ray emission 4,000 times greater than the sun does at solar maximum.

Image above: This artist's concept illustrates how the most extreme "pumpkin star" found by Kepler and Swift compares with the sun. Both stars are shown to scale. KSw 71 is larger, cooler and redder than the sun and rotates four times faster. Rapid spin causes the star to flatten into a pumpkin shape, which results in brighter poles and a darker equator. Rapid rotation also drives increased levels of stellar activity such as starspots, flares and prominences, producing X-ray emission over 4,000 times more intense than the peak emission from the sun. KSw 71 is thought to have recently formed following the merger of two sun-like stars in a close binary system. Image Credits: NASA's Goddard Space Flight Center/Francis Reddy.

These rare stars were found as part of an X-ray survey of the original Kepler field of view, a patch of the sky comprising parts of the constellations Cygnus and Lyra. From May 2009 to May 2013, Kepler measured the brightness of more than 150,000 stars in this region to detect the regular dimming from planets passing in front of their host stars. The mission was immensely successful, netting more than 2,300 confirmed exoplanets and nearly 5,000 candidates to date. An ongoing extended mission, called K2, continues this work in areas of the sky located along the ecliptic, the plane of Earth's orbit around the sun.

"A side benefit of the Kepler mission is that its initial field of view is now one of the best-studied parts of the sky," said team member Padi Boyd, a researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who designed the Swift survey. For example, the entire area was observed in infrared light by NASA's Wide-field Infrared Survey Explorer, and NASA's Galaxy Evolution Explorer observed many parts of it in the ultraviolet. "Our group was looking for variable X-ray sources with optical counterparts seen by Kepler, especially active galaxies, where a central black hole drives the emissions," she explained.

Using the X-ray and ultraviolet/optical telescopes aboard Swift, the researchers conducted the Kepler–Swift Active Galaxies and Stars Survey (KSwAGS), imaging about six square degrees, or 12 times the apparent size of a full moon, in the Kepler field.

"With KSwAGS we found 93 new X-ray sources, about evenly split between active galaxies and various types of X-ray stars," said team member Krista Lynne Smith, a graduate student at the University of Maryland, College Park who led the analysis of Swift data. "Many of these sources have never been observed before in X-rays or ultraviolet light."

Kepler Space Telescope (K2). Image Credit: NASA

For the brightest sources, the team obtained spectra using the 200-inch telescope at Palomar Observatory in California. These spectra provide detailed chemical portraits of the stars and show clear evidence of enhanced stellar activity, particularly strong diagnostic lines of calcium and hydrogen.

The researchers used Kepler measurements to determine the rotation periods and sizes for 10 of the stars, which range from 2.9 to 10.5 times larger than the sun. Their surface temperatures range from somewhat hotter to slightly cooler than the sun, mostly spanning spectral types F through K. Astronomers classify the stars as subgiants and giants, which are more advanced evolutionary phases than the sun's caused by greater depletion of their primary fuel source, hydrogen. All of them eventually will become much larger red giant stars.

Forty years ago, Ronald Webbink at the University of Illinois, Urbana-Champaign noted that close binary systems cannot survive once the fuel supply of one star dwindles and it starts to enlarge. The stars coalesce to form a single rapidly spinning star initially residing in a so-called "excretion" disk formed by gas thrown out during the merger. The disk dissipates over the next 100 million years, leaving behind a very active, rapidly spinning star.

Howell and his colleagues suggest that their 18 KSwAGS stars formed by this scenario and have only recently dissipated their disks. To identify so many stars passing through such a cosmically brief phase of development is a real boon to stellar astronomers.

Swift observatory. Image Credit: NASA

"Webbink's model suggests we should find about 160 of these stars in the entire Kepler field," said co-author Elena Mason, a researcher at the Italian National Institute for Astrophysics Astronomical Observatory of Trieste. "What we have found is in line with theoretical expectations when we account for the small portion of the field we observed with Swift."

The team has already extended their Swift observations to additional fields mapped by the K2 mission.

Ames manages the Kepler and K2 missions for NASA’s Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corp. operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

Goddard manages the Swift mission in collaboration with Pennsylvania State University in University Park, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan.

The eerie glow of a dead star, which exploded long ago as a supernova, reveals itself in this NASA Hubble Space Telescope image of the Crab Nebula. But don't be fooled. The ghoulish-looking object still has a pulse. Buried at its center is the star's tell-tale heart, which beats with rhythmic precision.

Image above: Astronomers discovered a real "tell-tale heart" in space, 6,500 light-years from Earth. The "heart" is the crushed core of a long-dead star, called a neutron star, which exploded as a supernova and is now still beating with rhythmic precision. Evidence of its heartbeat are rapid-fire, lighthouse-like pulses of energy from the fast-spinning neutron star. The stellar relic is embedded in the center of the Crab Nebula, the expanding, tattered remains of the doomed star. Image Credits: NASA and ESA, Acknowledgment: M. Weisskopf/Marshall Space Flight Center.

The "heart" is the crushed core of the exploded star. Called a neutron star, it has about the same mass as the sun but is squeezed into an ultra-dense sphere that is only a few miles across and 100 billion times stronger than steel. The tiny powerhouse is the bright star-like object near the center of the image.

This surviving remnant is a tremendous dynamo, spinning 30 times a second. The wildly whirling object produces a deadly magnetic field that generates an electrifying 1 trillion volts. This energetic activity unleashes wisp-like waves that form an expanding ring, most easily seen to the upper right of the pulsar.

The nebula's hot gas glows in radiation across the electromagnetic spectrum, from radio to X-rays. The Hubble exposures were taken in visible light as black-and-white exposures. The Advanced Camera for Surveys made the observations between January and September 2012. The green hue that gives the nebula a Halloween theme, represents the color range of filter used in the observation.

Animation above: This time-lapse movie of the Crab Nebula, made from NASA Hubble Space Telescope observations, reveals wave-like structures expanding outward from the "heart" of an exploded star. The waves look like ripples in a pond. The heart is the crushed core of the exploded star, or supernova. Called a neutron star, it has about the same mass as the sun but is squeezed into an ultra-dense sphere that is only a few miles across and 100 billion times stronger than steel. This surviving relic is a tremendous dynamo, spinning 30 times a second. The rapidly spinning neutron star is visible in the image as the bright object just below center. The bright object to the left of the neutron star is a foreground or background star. The movie is assembled from 10 Hubble exposures taken between September and November 2005 by the Advanced Camera for Surveys.Animation Credits: NASA and ESA, Acknowledgment: J. Hester (Arizona State University).

Hubble and the sunrise over Earth

The Crab Nebula is one of the most historic and intensively studied supernova remnants. Observations of the nebula date back to 1054 A.D., when Chinese astronomers first recorded seeing a "guest star" during the daytime for 23 days. The star appeared six times brighter than Venus. Japanese, Arabic, and Native American stargazers also recorded seeing the mystery star. In 1758, while searching for a comet, French astronomer Charles Messier discovered a hazy nebula near the location of the long-vanished supernova. He later added the nebula to his celestial catalog as "Messier 1," marking it as a "fake comet." Nearly a century later British astronomer William Parsons sketched the nebula. Its resemblance to a crustacean led to M1's other name, the Crab Nebula. In 1928 astronomer Edwin Hubble first proposed associating the Crab Nebula to the Chinese "guest star" of 1054.

The nebula, bright enough to be visible in amateur telescopes, is located 6,500 light-years away in the constellation Taurus.

The international effort to find, confirm and catalogue the multitude of asteroids that pose a threat to our planet has reached a milestone: 15 000 discovered – with many more to go.

The number of catalogued asteroids approaching Earth has grown rapidly since the count reached 10 000 only three years ago.

Near-Earth objects, or NEOs, are asteroids or comets with sizes ranging from metres to tens of kilometres whose orbits come close to ours, meaning they could hit our planet.

The discovered NEOs are part of a much larger population of more than 700 000 known asteroids in our Solar System.

Asteroid Lutetia

“The rate of discovery has been high in the past few years, and teams worldwide have been discovering on average 30 new ones per week,” says Ettore Perozzi, manager of the NEO Coordination Centre at ESA’s centre near Rome, Italy.

“A few decades back, 30 were found in a typical year, so international efforts are starting to pay off. We believe that 90% of objects larger than 1000 m have been discovered, but – even with the recent milestone – we’ve only found just 10% of the 100 m NEOs and less than 1% of the 40 m ones.”

Today, the two main discovery efforts are in the US: the Catalina Sky Survey in Arizona, and the Pan-STARRS project in Hawaii, jointly accounting for about 90% of the new bodies found.

Chelyabinsk asteroid trail

ESA is contributing through its Space Situational Awareness programme, setting up the centre in Italy to combine new and existing European telescope data and support a new network to distribute information.

“There is only a tiny impact probability for any known object in the next 40 years, but all NEOs bear close watching to refine and understand their orbits.”

The coordination centre is also the focal point for scientific studies needed to improve warning services and provide near-realtime data to scientific bodies, international organisations and government decision-makers.

In recent years, astronomers working with or sponsored by ESA have concentrated on follow-up observations, confirming new objects and obtaining more reliable orbits. Some of this work was done with ESA’s own observatory on Tenerife in the Canary Islands.

Others have been instrumental in imaging or confirming the orbits of particularly interesting objects, such as asteroid 2016 RB1, which grazed our planet on 7 September 2016 by 34 000 km, within the orbit of many telecom satellites.

Future fly-eye telescope

In the coming years, the pace of discovery is likely to increase.

ESA is developing new ‘fly eye’ telescopes to conduct automated nightly wide-sky surveys with their very large fields of view. These are expected to begin operating around 2018. The Large Synoptic Survey Telescope, being built in Chile, is set to begin hunting space rocks in the near future.

These future telescopes offer the almost complete sky coverage and depth needed for humanity to be sure that as many NEOs as possible are discovered and identified before posing any threat.

A high-resolution image taken by a NASA Mars orbiter this week reveals further details of the area where the ExoMars Schiaparelli module ended up following its descent on 19 October.

The latest image was taken on 25 October by the high-resolution camera on NASA’s Mars Reconnaissance Orbiter and provides close-ups of new markings on the planet’s surface first found by the spacecraft’s ‘context camera’ last week.

Zooming in on Schiaparelli components on Mars

Both cameras had already been scheduled to observe the centre of the landing ellipse after the coordinates had been updated following the separation of Schiaparelli from ESA’s Trace Gas Orbiter on 16 October. The separation manoeuvre, hypersonic atmospheric entry and parachute phases of Schiaparelli’s descent went according to plan, the module ended up within the main camera’s footprint, despite problems in the final phase.

The new images provide a more detailed look at the major components of the Schiaparelli hardware used in the descent sequence.

The main feature of the context images was a dark fuzzy patch of roughly 15 x 40 m, associated with the impact of Schiaparelli itself. The high-resolution images show a central dark spot, 2.4 m across, consistent with the crater made by a 300 kg object impacting at a few hundred km/h.

The crater is predicted to be about 50 cm deep and more detail may be visible in future images.

The asymmetric surrounding dark markings are more difficult to interpret. In the case of a meteoroid hitting the surface at 40 000­–80 000 km/h, asymmetric debris surrounding a crater would typically point to a low incoming angle, with debris thrown out in the direction of travel.

Schiaparelli landing site

But Schiaparelli was travelling considerably slower and, according to the normal timeline, should have been descending almost vertically after slowing down during its entry into the atmosphere from the west.

It is possible the hydrazine propellant tanks in the module exploded preferentially in one direction upon impact, throwing debris from the planet’s surface in the direction of the blast, but more analysis is needed to explore this idea further

An additional long dark arc is seen to the upper right of the dark patch but is currently unexplained. It may also be linked to the impact and possible explosion.

Finally, there are a few white dots in the image close to the impact site, too small to be properly resolved in this image. These may or may not be related to the impact – they could just be ‘noise’. Further imaging may help identify their origin.

Mars Reconnaissance Orbiter view of Schiaparelli landing site

Some 1.4 km south of Schiaparelli, a white feature seen in last week’s context image is now revealed in more detail. It is confirmed to be the 12 m-diameter parachute used during the second stage of Schiaparelli’s descent, after the initial heatshield entry into the atmosphere. Still attached to it, as expected, is the rear heatshield, now clearly seen.

The parachute and rear heatshield were ejected from Schiaparelli earlier than anticipated. Schiaparelli is thought to have fired its thrusters for only a few seconds before falling to the ground from an altitude of 2–4 km and reaching the surface at more than 300 km/h.

In addition to the Schiaparelli impact site and the parachute, a third feature has been confirmed as the front heatshield, which was ejected about four minutes into the six-minute descent, as planned.

The ExoMars and MRO teams identified a dark spot last week’s image about 1.4 km east of the impact site and this seemed to be a plausible location for the front heatshield considering the timing and direction of travel following the module’s entry.

The mottled bright and dark appearance of this feature is interpreted as reflections from the multilayered thermal insulation that covers the inside of the front heatshield. Further imaging from different angles should be able to confirm this interpretation.

The dark features around the front heatshield are likely from surface dust disturbed during impact.

Zooming in on Schiaparelli landing site

Additional imaging by MRO is planned in the coming weeks. Based on the current data and observations made after 19 October, this will include images taken under different viewing and lighting conditions, which in turn will use shadows to help determine the local heights of the features and therefore a more conclusive analysis of what the features are.

A full investigation is now underway involving ESA and industry to identify the cause of the problems encountered by Schiaparelli in its final phase. The investigation started as soon as detailed telemetry transmitted by Schiaparelli during its descent had been relayed back to Earth by the Trace Gas Orbiter.

The full set of telemetry has to be processed, correlated and analysed in detail to provide a conclusive picture of Schiaparelli’s descent and the causes of the anomaly.

Until this full analysis has been completed, there is a danger of reaching overly simple or even wrong conclusions. For example, the team were initially surprised to see a longer-than-expected ‘gap’ of two minutes in the telemetry during the peak heating of the module as it entered the atmosphere: this was expected to last up to only one minute. However, further processing has since allowed the team to retrieve half of the ‘missing’ data, ruling out any problems with this part of the sequence.

The latter stages of the descent sequence, from the jettisoning of the rear shield and parachute, to the activation and early shut-off of the thrusters, are still being explored in detail. A report of the findings of the investigative team is expected no later than mid-November 2016.

The same telemetry is also an extremely valuable output of the Schiaparelli entry, descent and landing demonstration, as was the main purpose of this element of the ExoMars 2016 mission. Measurements were made on both the front and rear shields during entry, the first time that such data have been acquired from the back heatshield of a vehicle entering the martian atmosphere.

The team can also point to successes in the targeting of the module at its separation from the orbiter, the hypersonic atmospheric entry phase, and the parachute deployment at supersonic speeds, and the subsequent slowing of the module.

These and other data will be invaluable input into future lander missions, including the joint European–Russian ExoMars 2020 rover and surface platform.

Finally, the orbiter is working well and being prepared to make its first set of measurements on 20 November to calibrate its science instruments.